Method of form grinding



June 555, 1932- W. E... HUTCHHNSON ET AL 9 3 METHOD OF FORM. GRINDING Filed Sept. 21, v1929 2 Sheet-Sheet 1 JM WM Z 7r= *V 1Z a y I INVENTORS fiotsmr/ Ram 5 #14441. 75/? Z f/urc/rm/sm E ATTORNEY 'June 28, 1932- w. L. HUTCHINSON ET AL 3 9 METHOD OF FORM GRINDING Filed Sept. 21, 1929 2 Sheets-Sheet 2 INVENTORS Fatented Jame .28,

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This invention relates to form grinding and particularly to grinding the bottom of a groove and the sides of the flanges of such groove by the application of the perimeter only of the grindin wheel to the work piece, the wheel moving into and out of the work in a direction following the geometrical lines of the sides of the grinding wheel.

For the purpose of best illustrating the inm vention reference may be had to the accompanying drawings, in which Figure 1 is supposed to represent a preformed piece of work which is intended to be finished within precision tolerances and is which is adapted for treatment by our improved method.

Fig. 2 shows the work piece of Figure 1 receiving the treatment of a roughing wheel.

Fig. 3 represents the product of the roughso ing step.

Fig. 4 shows a grinding wheel reducing the sides of the flanges and the bottom of the groove of such piece.

Fig. 5 represents the product of the Fig.

25 a step and shows the wheel backed out of the work for dressing.

Fig. 6 represents the newly dressed wheel going into the work for the finishing operation.

Fig. 7 is an enlarged view to represent schematically and out of proportion the fact that in the Fig. 4c and Fig. 6 steps the sides of the grinding wheel are out of contact with the side flanges, and that the entire grinding operation is efiected by the circumferential face or perimeter of the grinding wheel.

Fig. 8 shows the invention applied to the formation of a groove having the faces of the flanges spherical and generated upon a common center, one of such faces being concave and the other convex, and

Fig. 9 shows the wheel backed out of the work for dressing the grinding face.

This method having been perfected in the grinding of rings for roller bearings it has been deemed best to illustrate the grinding in connection with the rings of such bearings. In both forms the inner ring has been chosen for illustration.

Figure 1 shows as a work piece a pre-formed tit) inner ring 10 of a cylindrical roller bearing which has the circumferential groove 11 part- 1y completed, there being two flanges 12 at the sides of this groove. in the finished prodnot, see Fig. 6, the inner side faces 13 of these flanges 12 are disposed in parallel planes which are radial of the axis of the bore 14: of the ring, and are also radial of the raceway surface 15 of the groove 11.

The piece of work upon which the process commences its operation is in the prevailing practice of roller bearing manufacture a blank which has been machined from suitable steel and hardened. And generally at the present time the scale will previously have been removed by means of a sand blast tumbling barrel. This workpiece represented in Figure 1 is preferably as a preliminary step subjected at the bottom of the groove 11 to the abrasive action of a roughing wheel 16, the width 17 of which is slightly less than the distance apart 18 of the unfinished sides of the flanges 12.

lhe product of this step of preparing the work piece for the more important steps of my process is represented in Fig. 8. The bottom 19 of the groove having been roughly dressed by the wheel 16 leaves, it will be seen, corners or lands 20 which have not been removed. Uf course it is to be understood that the clearances illustrated herein are not conformative with practice, since it is very difficult to show these delicate operations in proportion in a pen and ink drawing.

Une of the problems which our process has solved is the complete finishing within precision tolerances of the faces 13 of the flanges 12, the bottom 15 of the groove 11, the unground sides 21, and the corners 20 of the roughly ground face 19 when this step is included. For accomplishing this purpose a grinding wheel 22 of suitable characteristics is employed which, by means of its shaft 23, is driven at a suitable speed. The ring 10 also is rotated at a suitable speed.

While applicants could very readily supply a chart showing the rates of speed at which they have driven the various parts in performing this process, yet there are so many factors and elements which enter into this matter that a table of speeds which were ac' complished upon one machine working upon a certain kind of steel which has been hardened and tempered and operated upon by a certain make of grinding wheel, might be of use, it is believed a practical grinder who desires to practise this invention will find no difficulty in arriving at speeds, feed and other factors in use.

The wheel 22 is prepared for use by having its side faces 24 dressed to conform to the lines upon which these faces will move when the wheel is being fed into the work. In Figs. 1 to 7 of the present illustration the wheel is fed into the work on a line which is perpendicular to its axis and which is per endicular to the face which is to be the y al product and arallel with the faces 13 of the sides of the anges. These side faces 24 of the wheel in this portion of the illustration are therefore plane faces which are parallel one with the other, and the width 25 of the wheel is practically the width or distance apart of the faces 13.

The working face 26 of the grinding wheel 22, which represents the circumference or outer perimeter of the wheel, is dressed to conform to the proposed finished bottom 15 of the groove of the finished product, in the present instance cylindrical. This face 26 is the working facethe grinding facesince the entire grinding operation is erformed by this face which enters the wor i, as in Fig. 4, grinding away from the outside inwardly of the faces 21 and the shoulders 20, when these are present, until they are reduced to a common plane. The grindin wheel then proceeds to cut into the face 2 7, see Fig. 5, producing the side faces 13 of the finished article.

After the Fig. 4 step the wheel 22 is backed above stated, and then a ain presented to the work, engaging the slig tfillets 29 with its freshly dressed corners, and finishes them and the face 27 into the cylindrical face 15 having square cornered junctures 30 with the flanges 13.

Fig. 7 is for the purpose of graphically illustrating the fact that the side faces 24 of the grinding wheel 22 do not engage the side faces 13 of the flanges with an abrasive action, and to demonstrate the fact that the grinding is done entirely by the outer perimeter of the grinding wheel.

The preceding descriptionhas been based on the simpler mode of carrying out our improved method wherein a cylindrical grinding wheel isused having radially disposed side faces. In Fig. 8 we have illustrated our method as employed for grinding spherical surfaces which are produced by moving the grinding wheel upon the sphere center of such surfaces.

The grinding wheel 32 is shown mounted on a broken away shaft 33. The axis of the shaft is assumed to be at a considerable distance from the wheel, the point :0 being represented but assumed to be at a considerable further distance away than the limitation the sheet of drawing paper will permit. The side face 34 of the wheel which is farthest away from the point a; is assumed to be spherical and generated about the point a". The side face 35 which is nearer the point :12 is a concave spherical face also generated from such common point, and it is around this point that the wheel 32 moves upon entering into and withdrawing from the work piece.

The perimeter of working face 36 of the wheel has a curved contour, it being a figure of rotation.

The work piece 37 which is supposed to be ground in this example of our invention is the inner ring of a roller bearing, the bottom 38 of the groove being concave, one of the flanges 39 having a concave spherical face 40, the other flange 41 having a convex spherical face 42, these spherical faces and 42 being also assumed to be generated from the distant common axial point.

When grinding by the mode represented in Fig. 8, the sides 34 and 35 of the wheel are permanently dressed to conform with the spherical contours which are to be. generated in the finished body. The perimeter 36 is the working face presented to the work, and as in the previous illustrative exam les, the entire grinding operation is eifecte by this face 36 as it enters the work on lines parallel with its side faces and parallel with the side faces which are generated in grinding. In this instance also it is found desirable, when the grinding of the groove has reached its approximate finished depth, to withdraw the wheel and dress the face 36 for the purpose of squaring or truing up the corners 43 so that when the wheel again enters the work it will grind out the fillets and sharpen the corners 44 of the groove.

Although but two illustrative examples of modes of carrying out our improved method have been illustrated, it will be apparent that changes may be made within the scope of the claims without departing from the spirit of our invention.

Having described our invention, we claim and desire to secure by Letters Patent:

1. The method of grinding which consists in pre-forming a round blank having upon aeeasea its perimeter a groove, the bottom and sides of which are to be finished, rotating the blank, then rough grinding the bottom of the groove only without reducing the sides, then presenting a grinding .wheel having a width equal to the distance apart of the proposed finished sides of the groove and a perimeter to conform with the proposed finished bottom of the groove to the work piece, and grinding the sides of the flanges from the outer perimeter inwardly by engagement with the perimenter of the grinding wheel, then backing oil' the grinding wheel from the work and dressing its perimeter, and then again presenting it to its work for the purpose of finishing the bottom of the groove and the corners formed at the juncture of the sides and bottom of the groove.

2. The method of form grinding grooves in rings, which consists in dressing the sides of a grinding wheel to lie in planes parallel with the line of proposed grinding movement of the wheel and dressing the perimeter of the wheel to conform with the proposed bottom of the groove, and rotating the ring, then presenting the grinding wheel to the ring by a relative feeding movement following the geometrical lines of the side faces of the wheel, the entire grinding operation being effected by the perimeter of the wheel its side faces not being in grinding or abrasive contact with the side faces of the groove which is being ground.

3. The method of grinding which consists in preforming a groove in the perimeter of a round blank the sides of which groove are to be finished as spherical segments having a common center, then dressing the sides of a grinding wheel to the spherical contour of the proposed finished sides, then presenting such wheel to the pre-formed groove and grinding the side of the flanges defining the groove from the outer perimeter inwardly by engagement with the perimeter of the grinding wheel by relative movement between the grinding wheel and the blank about the common center of the spherical surfaces of the proposed finished sides.

4. The method of grinding which consists in utilizing a pre-formed blank having a groove in its perimeter, the sides of which are to be finished as spherical segments generated about a common center, then dressing the sides of a grinding wheel to the spherical contour of the proposed finished sides and a perimeter to conform with the proposed finished bottom of the groove, then present ing such wheel to the preformed groove by a movement upon the generating center and grinding the sides of the flanges defining the groove from the outer perimeter inwardly by engagement with the perimeter of the grinding wheel, then backing ofi the grinding wheel from the work and dressing its perimeter,

* and then again presenting-it to its work for can 5) the purpose of finishing the bottom of the grooveand the corners formed at the juncture of the sides and bottom of the groove.

5..The method of form grinding grooves in rings which consists in dressing the sides of a grinding wheel to lie in parallel spherical planes, and dressing the perimeter of the wheel to conform with the proposed bottom of the groove, then presenting the grinding wheel to the work by a relative feeding movement following the geometrical lines of the side faces of the wheel, the entire grindaing operation being effected by the perimeter of the wheel its side faces not being in grinding or abrasive contact with the side faces of the groove which is being ground.

6. The method of form grinding grooves in rings which consists in dressing the sides of a grinding wheel to lie in parallel spherical planes, and dressing the perimeter of the wheel to conform with the proposed bottom of the groove, then presenting the grinding wheel to the work by a relative feeding movement upon the sphere center of the side faces on lines parallel with the side faces of the wheel, thereby concurrently generating spherical surfaces on the walls forming the sides of the groove.

7. The method of simultaneously grinding the bottom surface and both side faces in a groove having a spherical side face and having concentric spherical side faces, characterized in that a grinding wheel having both side faces spherical andof the same radius as the corresponding faces of the finished groove and with a perimeter corresponding in the profile to that of the bottom of the groove is fed toward the work by a relative swinging movement between the grinding wheel and the work about the common center of the spherical faces of the groove and grinding wheel.

8. The method of simultaneously grinding the bottom surface and one side face in a groove having a spherical side face charaeterized in that a grinding wheel having one side face spherical and of the same radius as the corresponding face of the finished groove and with a perimeter corresponding in profile to that of the bottom of the groove is fed toward the work by a relative swinging motion between the grinding wheel and the work about the common center of the spherical face of the groove and grinding wheel.

, 9. The method of grinding the side faces of races in roller bearings, characterized in that the tool of a form known per se consisting of a dish-shaped grinding wheel having concentric spherical surfaces and rotating about its polar axis, the common center of the said concentric surfaces being situated at the point of intersection of the axis of the circulatory feeding movement of the grinding wheel and the axis of rotation of the work,

with the result that the side faces form concentric spherical zones of the spherical wheel determined by the above mentioned center.

In testimony whereof we have hereunto set our hands this 17th day of September, 1929.

WALTER L. HUTCHINSON. ROBERT F. RUNGE. 

